Characteristics of giant optical pulsations from ruby

A method of laser modulation is described which produces fast, intense and controllable "giant" laser pulses by "Q-modulation." In experiments with ruby, pulses of peak power up to 15 MW and of duration less than 30 nsec have been studied. The principles of the technique are outlined and early experimental results reviewed. The temporal, spectral and spatial structure of giant pulses produced from ruby by a nitrobenzene Kerr cell modulator is reported. The pulse characteristics found to date yield information about the nature of various relaxation processes in ruby and point the way to further experiments to clarify many questions which are raised. The results a) set an upper limit of 10^-7sec on the E^-→2A^-relaxation time, b) show a shortening of upper-state relaxation time by about seven times under heavy pumping, c) show relaxation of excitation taking place across the laser line in microseconds, d) show progressive spectral broadening for shorter pulses to encompass most of the fluorescent line, e) show increasing asymmetry of spectral output for faster, more intense pulses, and f) show little broadening of beam divergence over normal, but with added structure.